Method of producing bulky yarn



y 11, 1967 YOSHIMASA FUJITA ETAL 3,330,896

METHOD OF PRODUCING BULKY YARN 7 Filed July 2, 1963 1N VENTORS. YOSH/MASA F UJ/ T A KAZUM/ NAKAGA WA KE/ TARO .S'H/MODA KOJ/ M/ YASH/ TA ATTORNE;

United States Patent 3,330,896 METHOD OF PRODUClNG BULKY YARN Yoshimasa Fajita, Kazumi Nakagawa, Keitaro Shimoda,

and Koji Miyashita, Saidaiji, Japan, assignors to American Cyanamid Company, Stamford, Conn., a corporation of Maine Filed July 2, 1963, Ser. No. 292,387 Claims priority, application Japan, July 12, 1962, 37/ 29,293 5 Claims. (Cl. 264-403) This invention relates to a method for making bulky yarns and fabrics of synthetic acrylic fibers, said bulky yarns and fabrics being stable under hot, humid conditions.

At present, the conventional process for making a bulky yarn or fabric of acrylic fibers involves the blending together of acrylic fibers of two types having two different properties; (a) a first type of fiber which exhibits high shrinkage upon the application of heat and (b) a second type of fiber which exhibits low shrinkage upon the application of heat. The yarns and fabrics made from such a blend of fibers spun together are heat treated so as to permit the high-shrinkage fibers to shrink. However, such a process has a serious drawback in that when the yarn is heat treated with hot water or steam to produce a bulk therein, and/or the yarn is subjected to heat in dyeing and other operations, it tends to become slim as it is flattened or the bulk is lost. Also, during handling and heating, such as in laundering of the fabrics, the yarn therein tends to become slim losing bulk.

It is an object of the present invention to provide a process for making bulky yarns and fabrics having an attractive appearance and free of the tendency to become slim during subsequent treatments at elevated temperature, such as in dyeing and laundering.

We have found that the above object may be accomplished by making such yarns or fabrics from multicomponent fibers of two dissimilar acrylonitrile polymeric components eccentrically disposed toward each other in distinct zones extending throughout the length of said fibers with adjoining surfaces in intimate adhering contact blended with low shrinkage fibers and spun together. These components in the multi-component fibers have a difference in thermal shrinkage as spun fibers which, upon heat treatment of the resulting fibers, causes these fibers to produce a good bulk by the formation of threedimensional coil crimps. However, when heat treated at temperatures sufficiently elevated to produce a satisfactory bulkiness in the resulting yarns of fabrics, it was found that these multi-component fibers could not satisfactorily be processed on conventional textile handling equipment, such as the conventional spinning equipment.

It is another object of this invention to provide a process for the formation of yarns and fabrics of multicomponent fibers utilizing conventional spinning equipment.

With the conventional spinning equipment, it is not only difiicult to carry out the spinning of crimpless fibers (as is well known), but an excessive crimp also makes spinning extremely difiicult. This is particularly true of multi-component fibers, for when such fibers are manufactured by a process including a high temperature heat treatment to which conventional acrylic fibers are subjected, a number of coil crimps occur in the fibers. As these fibers are then spun, they are liable to creep round the cylinder of the card, and ultimately, the spinning operation must be suspended.

As will be described in further detail in this specification, We have successfully solved this problem by initially inhibiting the occurrence of too many coil crimps during the manufacture of multi-component fibers by selecting 3,330,896 Patented July 11, 1967 compositions for the two components of such fibers having appropriate rates of shrinkage at various temperature and by controlling the temperature at which such fibers are heat treated during the manufacture thereof to preclude full development of the crimp and then allowing the crimps to fully develop in such fibers in the course of a subsequent heat treatment conducted after forming the multi-component fibers into yarns or fabrics.

It is still another object of the present invention to provide a process for the manufacture of a high quality multi-component fiber which does not give rise to too many coil crimps during its manufacture but which does give rise to a substantially larger number of such crimps upon heat treatment at the elevated temperature after forming into yarns or fabrics, wherein such fibers also possess properties desirable for use in textile products.

For a clearer and more detailed description of this invention and its relationship to the previously known process for preparing bulky yarns and fabrics, reference may be made to the subjoined description and the accompanying drawing wherein:

FIGURE 1 is a cross-sectional View of a bundle of multi-component fibers such as may be utilized in the practice of this invention;

FIGURE 2 is a schematic representation of the prior art type of bulky yarn utilizing a blend of high-shrink fibers and low-shrink fibers; and

FIGURE 3 is a schematic representation of a bulky yarn in accordance with the present invention.

The rnu1ti-c0mp0nent fibers employed in the practice of the present invention are each composed of two dissimilar acrylonitrile polymeric components eccentrically disposed towards each other in distinct zones extending throughout the length of such fibers with the adjoining surfaces in intimate adhering contact. Preferably, these fibers have cross-sections about as illustrated in FIGURE 1, wherein the dotted zone represents one component and the undotted zone represents the other component. These multi-component fibers are formed by concurrently spinning the two dissimilar acrylic polymer components into fibers by extrusion, coagulation, drawing, and heattreatment steps. The extrusion and coagulation steps are performed by apparatus now known to those skilled in the art. Examples of such apparatus are to be found in Kulp et al., U. S. Patent No. 2,386,173, issued Oct. 2, 1945; Calhoun, U. S. Patent No. 3,006,028, issued Oct. 31, 1961; and Fujita et al., U. S. application Ser. No. 208,884, filed July 10, 1962, now US. Patent No. 3,182,106 issued May 4, 1965, and assigned to the assignee of the present application.

The two components which make up the multi-component fibers may be selected from acrylonitrile polymers, copolymers, and graft-copolymers as well as mixtures thereof each containing at least about by weight of acrylonitrile. As will be described in more detail hereinafter, the difference in thermal shrinkage of the components is controlled by incorporating into any such polymer one or more additional ingredients.

Representative compounds which may be polymerized with acrylonitrile to form acrylonitrile polymerization products useful for the practice of this invention are compounds containing a single CHFC grouping, for instance, the vinyl esters and especially the vinyl esters of saturated aliphatic monocarboxylic acids, e.g., vinyl acetate, vinyl propionate, vinyl butyrate, etc., vinyl and viuylidene halides, e.g., the vinyl and vinylidene chlorides, bromides and fluorides; allyl-type alcohols, e.g., allyl alcohol, methallyl alcohol, ethallyl etc; allyl, methallyl and other unsaturated monohydric alcohol esters of monobasic acids, e.g., allyl and methallyl acetates, laurates, cyanides, etc.; unsaturated carboxylic acids (e.g., acrylic, itaconic,

and alkacrylic acids e.g., methacrylic, ethacrylic, etc.) and esters and amides of such acids (e.g., methyl, ethyl, propyl, butyl, etc., acrylates and methacrylates, acrylamide, methacrylamide, N-methyl, -ethyl, -propyl, -butyl, etc., acrylamides and methacrylamides, etc.); methacrylonitrile, ethacrylonitrile and other hydrocarbon-substituted acrylonitriles; unsaturated aliphatic hydrocarbons containing a single CH CH grouping, e.g., isobutylene, etc.; and numerous other vinyl, acrylic and other compounds containing a single CH CH grouping which are copolymerizable with acrylonitrile to yield thermoplastic copolymers. Alkyl esters of alpha, beta-unsaturated polycarboxylic acids may also be copolymerized with acrylonitrile to form copolyers, e.g., the dimethyl, -ethyl, -propyl, -butyl, etc., esters of maleic, fumaric, citraconic, etc., acids.

It is further possible to incorporate into said polymer other compounds containing the vinyl group, such as a vinylpyridine or an unsaturated sulfonic acid having polymeric ethylene bonds.

vinylpyridines which can be employed in making copolymers with acrylonitrile, and used as herein described, are vinylpyridines represented by the formula C H: C Hz and which include 2-vinylpyridine, 3-vinylpyridine and 4 vinylpyridine; methyl vinylpyridines represented by the formula (II) C H=C H2 and which include 2-methyl-3-vinylpyridine, 3-vinyl-4- methylpyridine, 3-vinyl-S-methylpyridine, 2-vinyl-3- methylpyridine, 2 vinyl 4 methylpyridine, 2-vinyl-5-methylpyridine, 2-vinyl-6-methylpyridine, 2-methyl-4-vinylpyridine and 3-methyl-4-vinylpyridine. The vinylpyridines embraced by Formula II are a preferred subgroup within a broader class of vinylpyridines that are advantageously employed in making copolymers which, in filamentary form, are used in practicing the present invention and which may be represented by the formula (III) CH=C H:

and wherein R represents a lower alkyl radical, more particularly a methyl, ethyl, propyl (including n-propyl and isopropyl) or butyl (including nbutyl, isobutyl, sec-butyl and tert.-butyl) radical. Other examples include 2-vinyl- 4,6-dimethylpyridine, the 2- and 4-vinylquinolines, 2-vinyl- 4,6-diethylpyridine and others embraced by the formula (IV) CH==CH2 5-n (H) n! wherein R represents a lower alkyl radical, examples of which have been given hereinbefore, and n represents an integer from 1 to 5, inclusive.

Representative unsaturated sulfonic acids which may be used include vinylsulfonic acid, allylsulfonic acid, methallylsulfonic acid, styrenesulfonic acid, etc.

Ordinarily, the molecular weight (average molecular weight) of the homopolymeric or copolymeric acrylonitrile, from which the polyacrylonitrile shaped articles are made, is within the range of 25,000 or 30,000 to 200,- 000 or 300,000 or higher, and advantageously is of the order of 50,000 to 100,000, e.g., about 70,000-80,000, as calculated from a viscosity measurement of the said polymerization product in dimethyl formamide using the Staudinger equation (reference: Houtz US. Patent No. 2,404,713, dated July 23, 1946).

To be suitable for the practice of this invention, the two components forming the multi-component filament ordinarily should have a difference in thermal shrinkage as spun fibers of less than about 4% at 100 C. and at least about 5.5% at 115 C. in order that during the performance of the process of this invention, a relatively small number of crimps may be developed prior to forming the resulting fibers into a yarn or fabric and a substantially larger number of crimps may be developed by a subsequent heat treatment of the yarn or fabric at a more elevated temperature. These two dissimilar acrylonitrile polymeric components may differ from each other in having different monomers copolymerized with acrylonitrile or in having the same monomers copolymerized in defferent proportions with acrylonitrile so as to provide the proper difference in thermal shrinkage. The critical criterion is that the two components must provide a multicomponent fiber which does not give rise to more than about 5 coil crimps per 25 mm. at a temperature sufficiently high to satisfactorily heat treat the fiber after drawing but which does give rise to at least about 10 coil crimps per 25 mm. upon being heat treated after such fibers are formed into yarns or fabrics. This critical re- -quirement results from the difficulty in processing on spinning equipment coil crimped fibers having more than about 5 coil crimps per 25 mm. and from the fact that less than about 10 coil crimps per 25 mm. does not provide sufiicient bulkiness in the final product.

The characteristic of coil crimp in a multi-component fiber depends upon the difference in composition and thermal shrinkage of the two components comprising such a fiber, the temperature at which such fiber is heat treated, and the denier of the fiber. The degree of thermal shrinkage of the two components comprising a multi-component fiber may be controlled by controlling the proportion of ingredients to be contained in each component, i.e., acrylonitrile and other monomers copolymerized therewith, examples of which have been given above. Generally speaking, the rates of shrinkage of the two components generally increase with increase in the proportion of other vinyl compounds copolymerized with the acrylonitrile. Additionally, the amount of shrinkage of the two components increases with increase in temperature at which the fiber is heat treated. Thus, it is readily possible to select pairs of components which have a differential thermal shrinkage of less than a certain amount at one temperature and greater amount of thermal shrinkage at a more elevated temperature.

The number of coil crimps produced on heat treatment of such a multi-component fiber is a function of the difference in the thermal shrinkage of the components comprising such fiber as Well as the denier of such fiber. For a given size fiber, the higher the difference in thermal shrinkage achieved by the fiber, the larger the number of coil crimps per unit of length that will be produced. Thus, the selection of a pair of components having less than a certain difference in thermal shrinkage at a first temperature and greater than a higher difference of thermal shrinkage at a more elevated temperature permits the production of fibers having relatively few coil crimps by heat treating them below such certain temperature and permits the subsequent increase in the number of coil crimps by the later heat treatment at a temperature above the more elevated temperature.

Tables 1 and 2 show the coil crimp characteristics of multi-component filaments which are made up of copolymers containing acrylonitrile and 10% methyl acrylate (recipe A), 92% acrylonitrile and 8% methyl acrylate (recipe B), and 93% acrylonitrile and 7% methyl acrylate (recipe C), respectively.

NorE.Ihe d in the above table denotes the denier of each multicomponent filament.

TABLE 1 Temperature Rates of shrinkage, percent Numbers of coil crimps of heat- (per 25 mm.) treatment, C.

Recipe 0 Recipe A A-C 2d 3d 6d 10d NorE.The d in the above table denotes the denier of each multicomponent filament.

It will be apparent from the foregoing tables, that with respect to these copolymer filaments, the difference in the rate of shrinkage upon heat treatment at 100 C. is less than about 4% and that the difference in the rate of shrinkage upon heat treatment at 115 C. or more is greater than about 5.5%. It also will be noted that, in general, for any given temperature of heat treatment, a higher denier filament acquires fewer coil crimps per 25 mm. and that more coil crimps per 25 mm. are developed in any fiber of a given denier the higher the temperature of the heat treatment.

In the known processes for the manufacture of fibers from acrylonitrile polymers, it is considered essential that such fibers be heat treated in a relaxed state subsequent to drying and orientation and the minimum treating temperature for such process is in excess of 105 C. Such relaxation is described in US. Patent No. 2,883,260, issued Apr. 21, 1959, and US. Patent No. 2,614,289, issued Oct. 21,1952.

In the process for producing multi-component fibers according to the present invention, just as in the process for producing the conventional mono-component acrylic fibers, the aforementioned heat treatment in a relaxed state is an essential part of the process. The trouble is, however, that if a multi-component filament is heat treated at sufi'iciently elevated temperatures (e.g., over 100 C.) too many coil crimps occur in the fibers in this early stage of the process. Such a fiber having excessive three-dimensional coil crimps has various drawbacks, such as the tendency toward creeping round the card, which tendency makes spinning the fibers into threads practically impossible.

We have found an interesting relationship between the heat treatment temperature and the coil crimping characteristics of the two components comprising a multicomponent fiber due to the difference in their rates of shrinkage as illustrated in Tables 1 and 2 above. Based on this finding, we have devised a method for producing bulky yarns and fabrics from a blend of multi-component fibers and low shrinkage fibers which comprises selecting the compositions of the two acrylonitrile polymer components for the multi-component fibers such that the difference in shrinkage between them is at least about 5.5% at 115 C. so as to provide for adequate numbers of coil crimps in the final product but is less than about 4% at C. The process involves inhibiting the occurrence of excessive numbers of coil crimps during the manufacture of the fibers by maintaining the treating temperatures at all stages of the process subsequent to spinning and drawing and prior to carding (and particularly the temperature at which the fiber is heat treated in a relaxed state) below about 100 C. so as to facilitate the carding of such fibers. Subsequent to such carding operation, the textile product is heat treated at a temperature over C. thereby producing a sufiicient number of coil crimps to give a good bulk to the blended fibers and, at the same time, improve the overall physical properties of the multi-component fibers.

While it is true that the higher the temperature at which this final heat-treatment is conducted, the greater the number of coil crimps that are produced in the fiber and, therefore, the greater the bulkiness in the yarn or fabric, the preferred range is 115 C. to about C. since excessively higher temperatures might degrade the acrylic fibers or tend to cause yellowish discoloration thereof. This heat treatment can be conducted under either hot-dry or hot-wet conditions, such as by the use of heated air or other gases, superheated steam, saturated steam at superatmospheric pressure, boiling water under superatmospheric pressure, heated non-aqueous liquids, etc.

FIGURES 2 and 3 show schematic views, respectively, of a bulky conventional yarn and a bulky yarn made according to the present invention. As illustrated schematically in FIGURE 2, the conventional bulky yarn is composed of two different kinds of fibers; (a) high shrinking fibers, represented by the heavier lines, which tend to constitute the core of the yarn and (b) low shrinking fibers, shown as fine lines, which tend to constitute the sheath of the yarn. Since the low shrinking fibers tend to migrate to the outside of the yarn bundle during the bulking operation, they are liable to get loose from the bulky yarn during subsequent handling. Additionally, this yarn tends to become slim in the course of various subsequent processings to which textile products may be sub- 'jected, such as the heat treatment to produce the bulkiness, dyeing, laundering, and other heating processes, and the degree of slimness progresses as such processes are repeated.

In contrast, as schematically illustrated in FIGURE 3, the bulky yarn of this invention is made from a plurality of multi-component fibers, all of which form coil crimps upon heat treatment, and a plurality of low shrinkage fibers. The previously described mu-lticomponent fibers are blended with low shrinkage fibers prior to development of the full crimp in the multi-component fibers. The low shrinking fibers which can be used with the foregoing multi-component acrylic fibers include ordinary acrylic fibers, such as spun from the acrylonitrile polymers previously described, or other natural or synthetic fibers, such as wool, cotton, rayon, nylon, polyester, viny-l polymers and co-polymers, glass, etc.

The blend of low shrinking fibers and multi-component fibers in accordance with this invention should contain preferably at least 30% multi-component filaments and still more preferably more than 50% thereof. When less than about 30% multi-component filaments are used in a blend with low shrinking mono-component filaments, the resulting yarn, after full development of the coil crimp in the multi-component fibers, will be insufficiently bulky, with the kind of hand which is generally associated with the absence of bulky yarns.

Since the large number of coil crimps produced in the multi-component fibers so inter-twine each multi-component fiber with its adjacent fibers, it is extremely difiicult for any fibers to get loose from the bulky yarn. For these reasons, the bulky yarn produced in accordance with this invention is additionally characterized by the uniform density of fibers throughout the yarn and, more important, by the high stability of this bulkiness during subsequent heat treatments because the coil crimps are not eliminated by heat treatments, whether dry-heat or wetheat is used. Thus, the bulky yarn of this invention, once made bulky, would not become slim no matter how often heating is repeated. Therefore, this yarn possesses a high degree of solidity throughout, so that it can withstand repeated dyeings and launderings.

Another advantages of this invention is that, whereas the conventional bulky yarn suffers a loss of yarn strength during manufacture when the bulk is produced therein, the bulky yarn of the present invention shows an increase in yarn strength upon being subjected to a treatment to produce the bulk in the yarn.

EXAMPLE 1 A spinning solution of a copolymer composed of 90% acrylonitrile and 10% methyl acrylate in a concentrated aqueous solution of sodium thiocyanate was extruded into an 8% aqueous solution of sodium thiocyanate. The tow thus obtained was washed in water, drawn in boiling water to 800% the initial length, and dried in air at a drybulb temperature of 105 C. and a wet-bulb temperature of 70 C. until the filaments contained less than 3% of moisture. The dried filaments were treated in a relaxed state for 10 minutes in saturated water vapor at 120 0, followed by mechanical crimping, oil treatment, cutting, and drying to produce a regular yarn (A) of 3 denier. Another tow made under conditions similar to the above was drawn 130% between hot plates at 120 C. and cut to prepare an after-drawn yarn (B).

On the other hand, a copolymer composed of 90% acrylonitrile and 10% methyl acrylate, and another copolymer composed of 95% acrylonitrile and 5% methyl acrylate, respectively, were dissolved in concentrated aqueous solutions of sodium thiocyanate to prepare two different spinning solutions. Equal amounts of the two solutions were simultaneously extruded into an 8% aqueous solution of sodium thiocyanate by means of an apparatus similar to the one disclosed in US. Patent application Ser. No. 208,884, filed July 10, 1962, which is furnished with two metering pumps. The filaments thus prepared were washed with water, and drawn in boiling water to 800% the initial length.

The spinnerette contained 500 orifices each of which measured 0.08 millimeter in diameter, The filaments were then dried in a highly humid atmosphere, i.e. at a dry-bulb temperature of 100 C. and a wet-bulb temeperature of 70 C., so that the filaments contained less than 3% of moisture. The filaments were further treated in a relaxed state for 10 minutes in boiling water, followed by mechanical crimping, oil treatment, and cutting to produce a multi-component fiber staple (C).

A bulky yarn was produced by spinning together A and B in a proportion of 50:50 and, then, treating the resulting yarn in saturated Water vapor at 120 C. for 5 minutes.

On the other hand, a bulky yarn was manufactured by spinning together C and A in a proportion of 70:30 and, then, treating the resulting yarn in saturated water vapor at 120 C. for 5 minutes.

The strength and elongation properties of the abovementioned two bulky yarns before and after the high-bulk treatments in saturated water vapor at 120 C. are shown in the following table.

8 While the bulky yarn produced from the blend of A and B showed slimness at various points, the bulky yarn made from the blend of A and C was full-bodied and had a superior hand owing to the coil crimps produced therein.

EXAMPLE 2 Following the procedure of Example 1, regular fibers (D) of 3 denier and after-drawn fibers (E) of 5 denier were manufactured from a copolymer containing 90% acrylonitrile, 9.25% methyl acrylate, and 0.75% methallylsulfonic acid.

On the other hand copolymers composed of 90% acrylonitrile, 9.25% methyl acrylate, and 0.75% methallylsulfonic acid, and 94% acrylonitrile, 4.5% methyl acrylate and 1.5% methallylsulfonic acid, respectively, were separately dissolved.

Equal amounts of the spinning solutions were extruded by means of a multi-component spinning apparatus furnished with two metering pumps, and multi-component fibers (F) of 3-denier were manufactured in the same manner as described with reference to the multi-component fibers of Example 1.

A bulky yarn was manufactured by mix-spinning D and E in a proportion of 40:60 and, then, treating the spun fibers in boiling water to produce a bulk therein.

Another bulky yarn was manufactured by spinning together F and D in a proportion of 50:50 and treating the resulting yarn in saturated water vapor at 125 C. for 5 minutes to give three-dimensional coil crimps to the fibers.

The results of a comparative dyeing test which was carried out with the bulky yarn made from D and E and the bulky yarn made from D and F in a boiling dye bath containing a cationic dyestufi' showed that whereas the former yarn had local slimness, the latter was found to be a very solid bulky yarn completely free from local slimness.

EXAMPLE 3 Just as in Example 1, regular fibers (G) of 3 denier and after-drawn fibers (H) of 3 denier were manufactured from a copolymer composed of acrylonitrile, 8% vinyl acetate, and 7% vinylpyridine. On the other hand, a copolymer composed of 85% acrylonitrile, 8% vinyl acetate, and 7% vinylpyridine and another copolymer comprising acrylonitrile, 5% vinyl acetate and 5% vinylpyridine were independently dissolved.

Equal amounts of the spinning solutions thus prepared were extruded concurrently with an apparatus similar to the one used in Example 1 which was equipped with two metering pumps. Thus, in the same manner as Example 1, multi-component fibers (I) of 3 denier were produced.

A bulky yarn was manufartured by mix-spinning fibers G and H in a proportion of 50:50 and, then, treating them in boiling water to produce bulkiness.

For comparison, bulky yarns were prepared by mixspinning fibers I and G in two dilferent proportions of 50:50 and 25 :75, and heat-treating the resulting yarns in saturated water vapor at C. for 5 minutes.

It was found that the bulky yarn made from G and H had local slimness, that the bulky yarn made from I and G in the proportion of 50:50 was highly solid and did not show local slimness upon subsequent dyeing, and that the yarn made from I and G in the proportion of 25:75 did not develop a good bulk but showed flatness upon subsequent dyeing.

We claim:

1. A process for making bulky yarns and fabrics of a blend of (a) crimped multi-component fibers of two dissimilar acrylonitrile polymeric components eccentrically disposed towards each other in distinct zones extending throughout the length of said fibers with adjoining surfaces in intimate adhering contact, said components being selected to have a difference in thermal shrinkage as spun fibers of less than about 4% at 100 C. and at least about 5.5% at 115 C. and (b) low shrinkage fibers; said process comprising concurrently spinning said two dissimilar acrylonitrile polymer components into fibers by extrusion, coagulation, drawing, and heat-treatment steps, all of such heat-treatment steps subsequent to the last drawing step being conducted at temperatures below about 100 C. forming a blend of the resulting multi-component fibers with low shrinkage fibers, forming the blended fibers into yarn or fabric, and, finally, heat-treating the yarn or fabric at a temperature above about 115 C. to develop the bulk therein by substantially increasing the crimps in said multi-component fibers.

2. A process as defined in claim 1 wherein said heattreatment steps applied to said multi-component fibers include relaxation subsequent to the last drawing step, said relaxation step being conducted at elevated temperatures below about 100 C.

3. A process as defined in claim 2 wherein said relaxation is performed in boiling water.

4. A process as defined in claim 1 wherein the step of forming the blend of multi-component fibers with low shrinkage fibers includes mechanically crimping said multicomponent fibers, forming said multi-component fibers into staple, and mixing said staple with low shrinkage staple fibers.

5. A process for making bulky yarns and fabrics of a blend of (a) crimped multi-component fibers of two dissimilar acrylonitrile polymeric components eccentrically disposed towards each other in distinct zones extending 3 throughout the length of said fibers with adjoining surfaces in intimate adhering contact, said components being selected to have a difference in thermal shrinkage as spun fibers of less than about 4% at C. and at least about 5.5% at C. and (b) low shrinkage fibers; said process comprising concurrently spinning said two dissimilar acrylonitrile polymer components into fibers by extuusion, coagulation, drawing, and heat-treatment steps, all of said heat-treatment steps subsequent to the last drawing step being conducted at temperatures below that at which about 5 coil crimps per 25 millimeters are developed, forming a blend of the resulting multi-component fibers with low shrinkage fibers, forming the blended fibers into yarn or fabric, and, finally, heat-treating the yarn or fabric at a temperature above that at which about 10 coil crimps per 25 millimeters are developed to develop the bulk therein by substantially increasing the crimps in said multicomponent fibers.

References Cited UNITED STATES PATENTS 2,789,340 4/1957 Cresswell.

2,931,091 4/1960 Breen 264168 2,985,940 5/1961 Weldon.

2,988,420 6/1961 Ryan et al. 264168 3,038,240 6/1962 Kovarik 264168 3,065,042 11/1962 Bradley 264l82 3,081,516 3/1963 Evans 28-72 X 3,146,574 9/1964 Earnshaw 28-72 X 3,182,106 5/1965 Fujita et al. 264168 3,264,705 8/1966 Kovarik 28-76 ALEXANDER H. BRODMERKEL, Primary Examiner.

F. S. WHISENHUNT, J. H. WOO, Assistant Examiners. 

1. A PROCESS FOR MAKING BULKY YARNS AND FABRICS OF A BLEND OF (A) CRIMPED MULTI-COMPONENT FIBERS OF TWO DISSIMILAR ACRYLONITRILE POLYMERIC COMPONENTS ECCENTRICALLY DISPOSED TOWARDS EACH OTHER IN DISTINCT ZONES EXTENDING THROUGHOUT THE LENGTH OF SAID FIBERS WITH ADJOINING SURFACES IN INTIMATE ADHERING CONTACT, SAID COMPONENTS BEING SELECTED TO HAVE A DIFFERENCE IN THERMAL SHRINKAGE AS SPUN FIBERS OF LESS THAN ABOUT 4% AT 100*C. AND AT LEAST ABOUT 5.5% AT 115*C. AND (B) LOW SHRINKAGE FIBERS; SAID PROCESS COMPRISING CONCURRENTLY SPINNING SAID TWO DISSIMILAR ACRYLONITRILE POLYMER COMPONENTS INTO FIBERS BY EXTRUSION, 